The present invention relates generally to projection systems and in particular to an overhead projection system and to an overhead projector support assembly.
Overhead projection systems are well known in the art and typically include a ceiling mounted projector that is spaced from and aimed downwardly at a generally planar display surface onto which projected images are to be displayed. Unfortunately, ceiling mounted projectors suffer from a number of disadvantages. For example, some types of ceilings such as drop tile ceilings, do not provide the necessary support structure for overhead projectors. As a result, structural reinforcements for ceilings of this nature are necessary before overhead projectors can be ceiling mounted. Also, HVAC and/or lighting may be positioned on the ceilings at the positions where it is necessary to mount the projectors. If so, the HVAC and/or lighting must be moved before the projectors can be mounted. Furthermore, ceiling mounted projectors typically require specialized power and signal wiring that must be installed in the ceilings. In addition, registering ceiling mounted projectors with display screens requires specialized skill and calculations on the part of installers and typically leads to the use of expensive projectors with zoom and lens shift capabilities. These above-described problems result in expensive and onerous installations.
Mounting a projector to a wall surface has also been considered. For example, U.S. Pat. No. 5,490,655 to Bates discloses a video/data projector and monitor ceiling/wall mount. The wall mount includes a wall support assembly fixedly secured to a wall surface. A pair of struts extends horizontally from the wall support assembly. A projector/monitor adapter is supported by the ends of the struts. The wall support assembly includes a strut adapter that rests between a pair of adapter plates extending from a wall plate. A fastener secures the strut adapter to the adapter plates in a manner to permit rotation of the adapter plate and hence, the struts about a vertical axis.
Although Bates discloses an assembly for supporting a projector that is to be secured to a wall surface, the Bates wall mount suffers disadvantages. When a load is placed on the wall mount, the entire load is taken up by the wall mount and the wall surface due to the fact that the wall mount is static. If the load is significant, the load may cause damage to the wall mount and/or the wall surface. In addition, if it is necessary to service the wall mount and/or the projector supported thereon, a ladder or other similar device must be used to gain access to the wall mount and/or projector. As will be appreciated, improved overhead projection systems are desired.
It is therefore an object of the present invention to provide a novel overhead projection system and a novel overhead projector support assembly.
According to one aspect of the present invention there is provided an overhead projection system comprising:
an overhead projector support assembly extending outwardly from a generally vertical support surface in a generally horizontal disposition;
a display screen having a display surface mounted on said support surface beneath said projector support assembly; and
a projector mounted on said projector support assembly and aimed to project images onto the display surface of said display screen.
Preferably, the projector support assembly is pivotably mounted on the support surface and is moveable from the generally horizontal disposition downwardly when a load is placed on the projector support assembly. A governor controls pivotal movement of the projector support assembly in a manner so that the boom pivots downwardly under a load generally at an unconstrained rate to avoid damage to the overhead projection system and/or support surface.
In a preferred embodiment, the governor is a damper and spring arrangement that automatically returns the projector support assembly to the generally horizontal disposition when the load is removed at a controlled generally constant rate. A releasable locking mechanism carried by the damper and spring arrangement is actuable to retain the projector support assembly in a downwardly extending condition.
In the preferred embodiment, the projector support assembly includes a single boom. The boom has one end pivotally coupled to the support surface. The projector is suspended from the opposite end of the boom with the damper and spring arrangement being disposed on the boom intermediate its ends. The damper and spring arrangement is constituted by a gas spring having one end fixed to the boom and an opposite end fixed to an element moveable along the boom. The moveable element moves along the boom towards the fixed end during downward pivoting of the boom thereby to compress the gas spring.
Preferably, the display screen is pivotally mounted on the support surface to allow the bottom of the display surface to be tilted towards the projector. The display screen may be a touch panel that generates control signals representing contacts with the touch panel. In this case, the overhead projection system further includes a computer that executes an applications program and provides image output to the projector. The touch panel, computer and projector form a closed loop to define an interactive display system whereby control signals generated by the touch panel are used by the computer to update the applications program and the image output provided to the projector. A console is disposed beneath the display screen and houses the computer.
In another embodiment, the support surface is an upright support member that is mounted on a wheeled cart. This allows the overhead projection system to be wheeled to the desired location making the overhead projection system fully portable.
According to another aspect of the present invention there is provided an overhead projection system comprising:
an overhead projector support assembly extending outwardly from a generally vertical support surface in a generally horizontal disposition;
a display screen having a display surface mounted on said support surface beneath said projector support assembly;
a projector mounted on said projector support assembly; and
at least one reflective surface positioned to reflect images projected by said projector onto said display surface.
In one form, the overhead projection system is used in a rear projection environment. In this case, the display screen is mounted on the support surface and positioned so that the display surface covers an opening therein. The display surface is translucent so images projected onto the back of the display surface are visible when looking at the front of the display surface. In one embodiment, the projector is aimed away from the support surface. A mirror is mounted on the projector support assembly adjacent a distal end thereof and is positioned to reflect projected images backward onto the display surface of the display screen. In another embodiment, the projector is aimed towards the support surface. A pair of mirrors is mounted on the projector support assembly. A first mirror is positioned in front of the projector and a second mirror is positioned behind the projector. The first mirror is positioned to reflect projected images away from the support surface onto the second mirror. The second mirror is positioned to reflect projected images backward onto the display surface of the display screen.
According to yet another aspect of the present invention there is provided an overhead projector support assembly comprising:
at least one boom adapted to extend outwardly from a generally vertical support surface in a generally horizontal disposition and to support a projector at a location spaced from said support surface;
at least one coupling element adapted to couple pivotally one end of said at least one boom to said support surface to enable said at least one boom to be pivoted downwardly from said generally horizontal disposition under a load; and
a governor to control pivotal movement of said boom.
According to still yet another aspect of the present invention there is provided a portable overhead projection system comprising:
a portable upright support member;
an overhead projector support assembly extending outwardly from said support member in a generally horizontal disposition;
a display screen having a display surface mounted on said support member beneath said projector support assembly; and
a projector mounted on said projector support assembly and aimed to project images onto the display surface of said display screen, wherein said projector support assembly is pivotable from said horizontal disposition downwardly when a load is placed thereon.
The present invention provides advantages in that since the projector support assembly, which supports the projector, and the display screen are mounted on the same support surface, the projector and the display screen can be registered consistently and quickly. Also, since the boom pivots downwardly at a generally unconstrained rate whenever a load is placed on the boom and since the pivotal movement is controlled by the governor, the potential for damage to the overhead projection system and/or the support surface is significantly reduced.
The present invention also provides advantages in that since the projector support assembly can be pivoted downwardly and locked in position, maintenance and servicing of the projector and related cabling is facilitated obviating the need for a ladder or other similar device.